Projectile-launching implement having multi-stage draw

ABSTRACT

A bow includes an upper limb and a lower limb. A restraint system stores energy in the upper limb and the lower limb via drawing a tensioning cable to a charged position. A bow string releases the energy stored in the upper limb and the lower limb by the restraint system when the bow string is drawn to a ready position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61/479,290, filed Apr. 26, 2011, entitled “Projectile-Launching Implement Having Multi-Stage Draw,” the disclosure of which is hereby incorporated by reference herein in its entirety.

INTRODUCTION

Projectile launching devices (such as bows) are used to launch projectiles (arrows) at targets. In general, bows that launch with greater force require greater strength on the part of the user to draw the bow back into a ready position (i.e., the draw weight is higher). While this may be acceptable for an able-bodied user, users who are less strong may not be able to easily draw the bow, or hold it in the ready position while aiming. To address this problem, compound bows that utilize a pair of pulleys or cams to reduce the force that the user must overcome have been developed. These bows, however, may not provide sufficient advantages for certain users, for example, youth that are learning the skills of archery, or the disabled who wish to enjoy the sport.

SUMMARY

In one aspect, the technology relates to a projectile-launching device positionable in a release position wherein the device is unable to launch a projectile, a ready position wherein the device is able to launch a projectile, and a hold position located between the release position and the ready position, wherein the projectile-launching device includes: a restraint system for preventing the device from being moved from the hold position directly to the release position; and a release mechanism for disengaging the restraint system so as to allow the device to be returned to the release position directly from the ready position, wherein the release mechanism disengages the restraint system when the device is moved to the ready position, and wherein the device is unable to launch the projectile from the hold position. In an embodiment, the projectile-launching device further includes a plurality of deflectable arms and at least one tensioning member connecting the plurality of arms. In another embodiment, of the projectile-launching device, the plurality of deflectable arms include: a superior primary limb and an inferior primary limb; and a superior secondary limb and an inferior secondary limb; and at least one tensioning member includes: a primary cable connecting the superior primary limb and the inferior primary limb; and a secondary cable connecting the superior secondary limb and the inferior secondary limb. In yet another embodiment, the restraint system holds the superior secondary limb and the inferior secondary limb in a deflected position, when the secondary cable is moved to a second cable drawn position. In still another embodiment, the release system deactivates the restraint system when the superior primary limb and the inferior primary limb are moved to a deflected position.

In an embodiment of the above aspect, the release system deactivates the restraint system when the primary cable is moved to a primary cable drawn position. In another embodiment of the projectile-launching device, the restraint system includes a ratchet and pawl located on at least one of the secondary limbs. In another embodiment, the release mechanism includes an engagement element located on at least one of the primary limbs. In yet another embodiment, the primary cable is configured to releasably engage a projectile. In still another embodiment, the projectile-launching device, further includes a gearbox and a gear system including a tensioning member pulley located in the gearbox, wherein the tensioning element is wrapped at least partially around the tensioning member pulley. In another embodiment, the gear system further includes a ratchet and a pawl releasably engaging the ratchet.

In another embodiment of the above aspect, the release mechanism disengages the ratchet from the pawl. In another embodiment, the release mechanism is a trigger. In yet another embodiment, the release mechanism disengages the ratchet from the pawl when a bow string is moved from an undrawn position to a drawn position. In still another embodiment, the gear system further includes an actuator pulley and an actuator cable wrapped at least partially around the actuator pulley. In another embodiment, a free end of the actuator cable extends from the gearbox.

In another aspect, the technology relates to a method of launching a projectile with a projectile-launching device having a release position, a hold position, and a ready position, the method including: moving the device from the release position to the hold position, wherein when in the hold position, the device is prevented from returning to the release position and from launching the projectile from the hold position; moving the device from the hold position to the ready position, wherein when in the ready position, the device is enabled to return to the release position and to launch the projectile; and releasing the device from the ready position to the release position to launch the projectile. In an embodiment, the method further includes automatically engaging a restraint mechanism when the device is moved from the release position to the hold position. In another embodiment, the method further includes automatically disengaging the restraint system when the device is moved to the ready position.

In another aspect, the technology relates to a bow having: an upper limb and a lower limb; a tensioning cable and restraint system whereby energy may be stored in the upper limb and the lower limb via drawing the tensioning cable to a charged position; and a bow string that, via drawing the bow string to a ready position, releases the energy stored in the upper limb and the lower limb by the restraint system.

Accordingly, the present technology utilizes components that allow for a multi-stage draw of a bow. The user draws the bow string back to a first or hold position, wherein release of the bow string at the hold position will not launch the projectile; instead, the bow will hold or otherwise store the energy. If used in a compound bow configuration, one embodiment contemplates utilizing a pawl or other locking element that will lock one of the cams in place. To release the projectile, the user must then draw the bow string to a second position, where the pawl or locking mechanism is disengaged, thereby allowing the projectile to be launched upon release of the bow string. This second position may be referred to as a ready or armed position. Any number of draw stages may be utilized. In certain cases, the number of stages may be limited by the size of the projectile-launching implement, the desired weight of the implement, or other factors.

In another embodiment, pairs of pulleys or cams (a dual-pulley pair configuration) on a bow system may be used to reduce the draw weight required for each stage of the draw. Even though the draw weight is reduced in each draw stage, the projectile launch force is unaffected because of the multi-stage draw required to use the bow. In certain embodiments, in fact, the projectile launch force may be higher than that of existing compound bows utilizing a single pair of pulleys.

Another possible solution for reducing the effective draw weight is to utilize a reducing gear. The draw weight for each stage may be reduced by any desired ratio, but in certain embodiments, a draw weight reduction of half for each of the two draws may be desirable. In such an embodiment, as the user draws the bow to full draw, the limbs would only move about 50% of the full movement. The user would only feel 50% of the weight based on a 2:1 reduction. A ratchet and pawl system would hold the weight of the first draw at the first or hold position. The ratchet and pawl system would release towards the end of the second draw, at the second or ready position. In practice, a user would draw 60 lbs., twice, in order to have an effective release weight of 120 lbs. One advantage of this reducing gear configuration includes reducing the number of moving parts that would need to be synched and tuned to obtain the desired results. Losses due to friction are also substantially reduced. As described above with regard to the dual-pulley pair configuration, any number of draw stages may be utilized. In certain cases the number of draw stages may be limited by the size of the projectile-launching implement, manufacturing costs, desired implement weight, etc. Other embodiments utilizing different numbers of stages, reductions, etc. are contemplated and described below.

BRIEF DESCRIPTION OF THE DRAWINGS

There are shown in the drawings, embodiments which are presently preferred, it being understood, however, that the technology is not limited to the precise arrangements and instrumentalities shown.

FIGS. 1A-1I depict side views of a compound bow having a multi-stage draw in various positions.

FIG. 2 depicts a side view of a pawl for use in a bow having a multi-stage draw.

FIG. 3 depicts a side view of a ratchet for use in a bow having a multi-stage draw.

FIG. 4 depicts a partial enlarged perspective view of the compound bow of FIG. 1A.

FIG. 5A depicts a perspective view of a compound bow having a multi-stage draw.

FIGS. 5B and 5C depict an end view and a side view, respectively, of the compound bow of FIG. 5A.

FIG. 6 depicts an enlarged top view of a gear system utilized in a bow having a multi-stage draw.

FIGS. 7A-7C depict enlarged perspective views of sections of the gear system of FIG. 6.

DETAILED DESCRIPTION

Referring to FIGS. 1A to 1I, one embodiment of a projectile-launching device in the form of a compound bow 100 is shown. The order of the figures is presented such that they progress sequentially through the various states of operation of the compound bow 100 to show differences and interactions among relevant design features. For the purpose of clarity, a secondary cable 182 and a portion of a primary cable 180 are depicted in FIG. 1A. It should be noted that both cables 180, 182 are strung generally as is typical for compound bows, unless otherwise indicated below. In the remaining figures, either cable is depicted, depending on their relevance to description. The position of the cable that is not depicted in each figure would be apparent to a person of skill in the art.

Referring to FIG. 1A, the compound bow 100 is shown in a static equilibrium position before the bow 100 has been drawn in any way. This position may be generally referred to as the release position. Because this is static state of the bow 100, FIG. 1A is primarily used for reference to identify the basic design features of the bow 100.

In the embodiment shown, the compound bow 100 includes a riser 150 defining a grip 152 and an arrow shelf 154. The grip 152 is shaped such that an archer's hand can grasp and support the compound bow 100 in all of the various operating states. The arrow shelf 154 supports a projectile, such as an arrow (not shown) while the compound bow is being drawn from the release position to a ready position, and during firing. The riser 150 further includes a pair of limb pockets 158, 160 disposed at opposite ends of the riser body 150. In one embodiment, the limb pockets 158, 160 are integral to the riser body 150. In an alternative embodiment, the limb pockets 158, 160 are separate components that are operably attached to the riser body 150.

The compound bow 100 also includes two pairs of deflectable arms. The first pair of arms includes a superior primary limb (SPL) 102 and an inferior primary limb (IPL) 104. The second pair of arms, which are located between the primary limbs 102, 104 include a superior secondary limb (SSL) 106 and an inferior secondary limb (ISL) 108. In this description, the terms “superior” and “inferior” refer to the position of the limbs relative to each other and to are used distinguish the limbs from each other. The terms “upper,” “lower,” “top,” and “bottom,” may also be used as those terms are typically understood. Of course, if the technologies described herein are used in a crossbow application, the terms “first,” “second,” “left,” and “right” may be used. In the depicted embodiment, each of limbs 102-108 includes two parallel identical arms. However, only one of each parallel arm is viewable in FIGS. 1A-1I because the views are from the side of the compound bow 100 wherein one arm is behind the other parallel arm. However, this arrangement can be readily seen in FIG. 4, described below.

FIG. 4 depicts a partial enlarged view of a portion of the IPL 104 and ISL 108. The IPL 104 includes two arms 104′, and the ISL 108 includes two arms 108′. In other embodiments, each of the IPL 104 and ISL 108 may be forked, such that there is a single point of connection for each limb 104, 108 at the lower limb pocket 160, and each limb 104, 108 splits at a location distal therefrom. The axle 178 spans the arms 108′ of the ISL 108 and provides a point of rotation for both the cam 106 and the ratchet 118. A pawl axle 120 e spans the arms 108′ of the ISL 108 to support the pawl 120. An engagement element or release element 122 extends from the IPL 104, as described below.

Returning to FIG. 1A, each of the limbs 102-108 is configured to deflect and thus store potential energy that will be released into a projectile when the compound bow 100 is allowed to move from the ready position to the release position. To enable such a function, the limbs 102-108 are each connected to the riser 150 via the limb pockets 158, 160. As shown, a first end 102 a of the SPL 102 and a first end 106 a of the SSL 106 are received into limb pocket 156.

In one embodiment, a limb bolt 158 extends through the limb pocket 156 and the limbs 102, 106 to retain the limbs 102, 106 within the pocket 156. In a similar fashion, a first end 104 a of the IPL 104 and a first end 108 a of the ISL 108 are received into limb pocket 160. In one embodiment, a limb bolt 162 extends through the limb pocket 160 and the limbs 104, 108 to retain the limbs 104, 108 within the pocket 162. It is noted that other means may be used for retaining the limbs 102-108 within the limb pockets 156, 160 besides with single bolts 158, 162. For example, the limbs 102-108 may be secured by a plurality of bolts or by non-mechanical elements, such as high-strength chemical adhesives or combinations of various elements.

In one embodiment, the limb pockets 158, 160 are provided with rounded edges and/or cushioning material to reduce potential point stress onto the limbs 102-108 by the limb pockets 158, 160. Reducing point stress locations in the assembly will reduce the chance of catastrophic failure of the compound bow 100. Such features are especially beneficial where the limb pockets 158, 160 are formed from metal and the limbs are formed from a composite or other plastic material.

Still referring to FIG. 1A, each limb 102-108 is provided with a rotatable cam 110-116. The rotatable cams 110-116 are specifically shaped for providing mechanical advantage when the compound bow is placed in the ready position such that a reduced holding force is required to retain the bow 100 in the ready position. When the cams 110-116 are in this position, they can be referred to as being in “let off” or being in the “let off position.” This function allows an archer to hold the compound bow 100 in the ready position for a longer period of time so that the archer can steady the bow 100 more effectively for enhanced accuracy.

As shown, the superior primary limb cam 110 is provided at a second end 102 b of the limb 102. The cam 110 is operably connected to the parallel arms of the SPL 102 by an axle 172 which spans the arms. Likewise, the inferior primary limb cam 112 is at a second end 104 b of the IPL 104. The cam 112 is operably connected to the parallel arms of the IPL 104 by an axle 174 which spans the arms. The superior secondary limb cam 114 is provided at a second end 106 b of the SSL 106. The cam 114 is operably connected to the parallel arms of the SSL 106 by an axle 176 which spans the arms. The inferior secondary limb cam 116 is provided at a second end 108 b of the ISL 108. The cam 116 is operably connected to the parallel arms of the ISL 108 by an axle 178 which spans the arms.

As stated above, the compound bow 100 includes a primary cable 180. The primary cable 180 is connected to the SPL 102 at a first end 180 a and to the IPL 104 at a second end 180 b. In one embodiment, each end 180 a, 180 b of the primary cable 180 may be split such that each split end may be attached to each of the limbs 102, 104 at the axles 172, 174. As typical for compound bows, the primary cable 180 wraps around each of the cams 110 and 112 between the two ends 180 a, 180 b. This arrangement allows for the primary limbs 102, 104 to be drawn into the ready position by sufficiently pulling the portion of the primary cable 180 extending between the two cams 110, 112.

In a similar arrangement to the primary cable, the compound bow 100 includes a secondary cable 182. The secondary cable 180 is connected to the SSL 106 at a first end 182 a and to the ISL 108 at a second end 182 b. In one embodiment, each end 182 a, 182 b of the secondary cable 182 may be split such that each split end may be attached to each of the parallel limbs 106, 108 at the axels 176, 178. As typical for compound bows, the secondary cable 182 wraps around each of the cams 114 and 116 between the two ends 182 a, 182 b. This arrangement allows for the secondary limbs 106, 108 to be drawn into a hold position by sufficiently pulling the portion of the secondary cable 182 extending between the two cams 114, 116.

Still referring to FIG. 1, the compound bow further includes a ratchet 118 and a pawl 120. The ratchet 118 and the pawl 120 form a restraint system for retaining the secondary limbs 106, 108 in the hold position after the secondary cable 182 has drawn the limbs 106, 108. In the depicted embodiment, the ratchet 118 is operably coupled to the inferior secondary limb cam 116. In one embodiment, the ratchet 118 and cam 116 are rotatable with respect to each other. The ratchet 118 and the cam 116 may be operably coupled such that rotation of the cam 116 is constrained by the ratchet 118 such that, when the ratchet 118 is prevented from rotating, the secondary limbs 106, 108 are prevented from moving from the hold position. The ratchet 118 may be operably coupled to the cam 116 by a torsion spring.

As best seen in FIG. 3, ratchet 118 includes circumferential groove 118 a that guides the secondary cable 182 and maintains alignment with respect to the thickness of the ratchet 118. In one embodiment, the groove 118 a is a concave groove. The ratchet 118 is also provided with a ratchet tooth 118 b configured to mate with a corresponding ridge 120 c on a pawl 120. The tooth 118 b also can be configured to prevent misalignment with the ridge 120 c. Adjacent to the ratchet tooth 118 b is a guide ramp 118 c that guides the pawl 120 over the ratchet 118 before engaging with the tooth 118 b. In order allow mounting and rotation of the ratchet 118, an axle hole 118 d is provided through which axle 178 may extend. In one embodiment, axle hole 118 d is provided with a press-fit sleeve bearing. The ratchet 118 is provided with an anchor hole 118 e and an anchor pin 118 f for securing the second end 182 b of the secondary cable. Alternative embodiments of the ratchet 118 may not include the groove 118 a or anchor hole 118 e.

Referring to FIG. 2, the pawl 120 is shown in greater detail. The pawl 120 includes a pawl release 120 a configured to engage with a corresponding contact surface 122 associated with the IPL 108 to release the pawl 120 from the ratchet tooth 118 b. The pawl includes a rounded backing 120 b and a ridge 120 c for reducing stress concentrators and engaging with the ratchet tooth 118 b, respectively. In the embodiment shown, and as best seen in FIG. 4, the pawl 120 is rotatably mounted between the parallel inferior secondary limbs 108 via an axle hole 120 d and a corresponding axle 120 e.

Returning back to FIG. 1A, each of the limbs 102-108 may be provided with a respective friction reducer 124-130. The friction reducer 124-130 is formed from a low friction material and acts to reduce friction between the superior limbs 102, 106 and between the inferior limbs 104, 108. As shown, a friction reducer 124 is provided on a lower surface of the SPL 102 while a corresponding friction reducer 130 is provided on an upper surface of the SSL 106. Accordingly, instead of the limbs 102, 106 coming into direct contact with each other when sufficiently drawn, the friction reducers 124, 128 are brought into contact with each other. Similarly, a friction reducer 126 may be provided on an upper surface of the IPL 104 while a corresponding friction reducer 128 may be provided on a lower surface of the ISL 108. Accordingly, instead of the limbs 104, 108 coming into direct contact with each other when sufficiently drawn, the friction reducers 126, 130 are brought into contact with each other. In such a configuration, the compound bow 100 will be more efficient due to a lower energy loss through friction between the adjacent limbs. In one embodiment, the friction reducers are ultra-high molecular weight (UHMW) polyethylene tape, though other materials are contemplated.

Referring to FIG. 1B, the compound bow 100 is shown when the secondary cable 182 connecting the superior and inferior secondary limb cams 114, 116 has been nearly fully drawn. This is considered to be the secondary draw phase because only the secondary limbs 106, 108 and associated cams 114, 116 are affected through movement of the secondary cable 182. The act of drawing the secondary cable 182 requires the archer to apply a force (draw weight) over a distance (draw length). The draw length increases as the draw weight increases. The friction between the secondary cable 182 and the cams 114, 116 cause the SSL cam 114 and the ISL cam 116 to rotate clockwise and counterclockwise, respectively. These cams 114, 116 are connected via the secondary cable 182 that squeezes the secondary limbs 106, 108 together, elastically deforming the limbs 106, 108 as a result of the cam rotations. The work done by the archer to apply the required force over the distance necessary to deflect the secondary limb sets 106, 108 is stored in the deflected limbs in the form of strain energy. In one embodiment, the ISL cam 116 is connected to the ratchet 118 with a torsion spring (not shown) which allows the two to rotate together as a result of drawing the secondary cable 182. The SSL 106 and the ISL 108 are shown in their deflected positions in FIG. 1B. Accordingly, the SSL and ISL cams 114, 116 and ratchet 118 are shown in their rotated positions. Because the primary cable 180 remains undrawn, the SPL 102 and the IPL 104 along with their respective cams 110, 112, all remain in their equilibrium positions.

Referring to FIG. 1C, the compound bow 100 is shown at a point slightly further along in the secondary draw phase. Note the secondary cable 182 is not depicted. In this state, the pawl 120 is in contact with, but not yet engaged with the ratchet 118. In one embodiment, a light torsion spring (not shown) is provided to keep the pawl 120 in contact with the ratchet 118 while the ratchet 118 is rotating but does not impede the rotation of the ratchet 180. In an alternative embodiment, once drawn to this position, the secondary cable 182 may be slowly returned to its equilibrium position. In such an embodiment, a torsion spring (not shown) attaching the ratchet 118 to the ISL cam 116 may be provided to cause the ratchet 118 to rotate clockwise. The clockwise rotation of the ratchet 118 effectively takes up the slack in the secondary cable 182 while maintaining a sufficient amount of tension in the cable 182 to keep the SSL cam 114 and the ISL cam 116 fully rotated which keeps the SSL 106 and ISL 108 in their maximum deflected positions. By keeping the secondary limb sets 106, 108 fully deflected, this preserves the strain energy stored in the secondary limb sets 106, 108.

Turning to FIG. 1D, and continuing with embodiment of the bow that does not include the above-described secondary cable slack take-up technology, the compound bow 100 is shown in a point even further along in the secondary draw phase. The ratchet 118 has rotated such that the pawl 120 slides over the ratchet tooth guide ramp 118 c. Once the pawl 120 has passed the edge of the ratchet tooth 118 b, the light torsion spring (not shown) attached to the pawl 120 forces it back into contact with the surface of the ratchet 118.

Referring to FIG. 1E, the bow 100 is shown after the drawn of the secondary cable 182 has been completed by the archer, thus placing the secondary limbs 106, 108, respective cams 114, 116, and cable 182 under the mechanical control of the release mechanism. As shown, the pawl 120 and ratchet 118 are engaging one another to store the strain energy input from the initial draw phase in the deflected secondary limbs 106, 108. Rotation of the ratchet 118 and, therefore, separation of the limbs 106, 108 is impeded by the pawl 120. The convex ridge 120 c on the surface of the pawl 120 that contacts the ratchet 118, mates to the geometrically opposite concave surface on the ratchet tooth 118 a and the two lock together as the pawl 120 is compressed between the ratchet tooth 118 and the axle 120 e locating the pawl 120 on the ISL 108. At this point, the archer will knock an arrow and prepare to initiate the primary draw phase in preparation to fire. It is noted that the surfaces on the ridge 120 c and the tooth 118 b do not necessarily have to be convex and concave, respectively. For example, the ridge 120 c could have a concave or flat surface while the tooth 118 b could have a convex or flat surface.

In some embodiments, it is desired to limit the initial secondary draw phase to a single cycle, especially where catastrophic failure may be possible with repeated cycles. One way in which the initial secondary draw phase may be limited to a single cycle is facilitated by the geometry of the pawl 120 and ratchet mechanism 118. Specifically, the single tooth 118 b on the ratchet 118 can be configured to provide only one contact surface for the pawl 120 and ratchet 118 to engage. Additionally, the location of the anchor hole 118 f where the secondary cable 182 is attached to the ratchet 118 allows the cable 182 to block the contact surfaces (e.g. 118 b, 120 c) in the event that the ratchet 118 could be made to complete an additional complete rotation. Furthermore, the attachment of the ratchet 118 to the ISL cam 116 restricts the degree to which the ratchet 118 can rotate. As such, the compound bow can be configured with multiple safety features in that the secondary cable would create a barrier between the contact surfaces so the pawl 120 could not engage the ratchet tooth 118 b to store that energy.

Referring to FIG. 1F, the compound bow 100 is shown near the conclusion of the primary draw phase at a point when the primary cable 180 is almost fully drawn. In this figure, the SSL 106, and ISL 108 are still in the deflected position, held in place by the interaction between the pawl 120 and ratchet 118 as described previously. Additionally, the SPL 102 and IPL 104 are now also being deflected. However, the deflection of these sets of limbs 102, 104 is a result from the interactions between the primary cable 180, SPL cam 110, and IPL cam 112, similar to the interactions described with respect to the secondary elements. As the SPL 102 and IPL 104 continue deflecting, their inner surfaces begin to contact the outer surfaces of the superior and inferior secondary limb sets. Friction at the interface of these contact surfaces is a source of inefficiency for the system. When the bow 100 is eventually fired, some of the potential energy stored in the bow will be converted into heat, noise, and vibration rather than being converted into kinetic energy used to accelerate the arrow. As stated previously, friction reducers 124-130, may be applied to these contact surfaces to reduce these losses due to friction.

FIG. 1G illustrates the interaction between the pawl 120 and ratchet 118 immediately following completion of the primary draw phase while the archer is holding the primary cable 180 at full draw. In this figure, the SPL cam 110 and IPL cam 112 have achieved their maximum rotations, and are in a let off state. The primary limbs 102, 104 have reached their maximum deflection and the pawl pressure release 120 a has been contacted by an IPL contact surface 122 causing the pawl 120 to rotate about its axle 120 e, disengaging the pawl 120 from the ratchet tooth 118 b. The IPL contact surface 122 may be on a surface of the IPL 104 or a projection mounted to or between the parallel arms that make up the IPL 104. At this point the bow 100 is ready to fire. Some time is usually taken by the archer to steady the aim and ensure a clean shot.

FIG. 1H shows the configuration of the bow 100 just prior to the archer releasing the primary cable 180 and firing an arrow. In this figure, the ratchet 118 has rotated a small amount in the counterclockwise direction, in embodiments where the secondary cable 182 is spooled around the ratchet 118, some of the secondary cable 182 is unspooled. As this happens, the SSL cam 114 and the ISL cam 116 rotate a small amount allowing the secondary limb sets 106, 108 to push outwards against the primary limbs 102, 104. This allows the secondary limbs 106, 108 to discharge energy to the system, meaning that the energy stored by the initial secondary draw phase has been released from the mechanical control of the pawl 120 and ratchet mechanism 118. The archer will feel an increase in the draw weight required to keep the primary cable 180 fully drawn, but the increase in draw weight should be well below the composite peak draw weight of the bow 100. Effectively, the archer is now holding the full peak draw weight of the bow 100; however, because the cams 110, 112 associated with the primary limbs 102, 104 are in let off, the archer will only be holding a fractional amount of the peak draw weight determined by the let off geometry of the cams. The UHMW tape 124-130 at the interface surfaces of the primary and secondary sets of limbs 102-108 are now in direct contact. The low coefficient of friction associated with the tape reduces losses due to frictional effects, making the conversion from potential energy stored in the limbs as strain energy, to kinetic energy used to accelerate the arrow a more efficient transition.

FIG. 1I shows the bow 100 after the primary cable 100 has been released by the archer, accelerating the arrow downrange toward the target. In this figure, the increased flexural rigidity of the secondary limbs 106, 108 causes them to continue pushing outwards against the primary limbs 102, 104. The cams associated with the superior limbs 110, 114 and the cams associated with the inferior limbs 112, 116 rotate in opposite directions. The ratchet 118 continues to rotate as it unspools more of the secondary cable 182. All of this happens very rapidly as the components of the bow 100 work in concert to accelerate the arrow. Once the arrow has left contact with the primary cable 180 and the residual vibrations throughout the system have ceased, the bow 100 is once again in the equilibrium or release position (see FIG. 1A) and the complete firing sequence as described herein may be repeated as necessary.

FIG. 5A-5C depicts a various views of a compound bow 500 having a multi-stage draw. The bow 500 includes a riser 502, a superior or upper limb 504, and an inferior or lower limb 506. Proximate an end of the superior limb 504 is a superior cam 508 and proximate an end of the inferior limb 506 is an inferior cam 510. As common for compound bows, a cable 512 is connected at a first end to a superior cam axle 514 and extends towards the inferior cam 510. The cable 512 is wrapped around a camming surface 516 of the inferior cam 510 then extends towards the superior cam 508. After wrapping around a camming surface 518 of the superior cam 508, the cable 512 is connected to an inferior cam axle 520. The portion of the cable 512 spanning the two camming surfaces 516, 518 may be referred to as a bow string 522. This bow string 522 may be integral with the cable 508 or comprise one or more of woven or unwoven strings that are attached at either end to end portions of two discrete cables. That is, one cable may be connected to the superior camming axle 514 and wrapped around the inferior camming surface 516 while another cable may be connected to the inferior camming axle 520 and wrapped around the superior camming surface 518. The free ends of these two cables may be then connected to ends of a discrete bow string 522. In certain embodiments, the two cables may be a relatively stiff wire or other high strength element, while the discrete cable string may be a more flexible element.

The depicted bow 500 also includes a tensioning cable 524 connected at each end to the superior cam axle 514 and the interior cam axle 520. The tensioning cable 524 is passed into a gearbox 526 via an upper opening 528 and a lower opening 530. The gearbox 526 may be secured to the riser 502 by an upper rod 532 and a lower rod 534. The rods 532, 534 need only extend from the riser 502 to the gearbox 526, and the dimensions and/or profiles thereof are not critical. Moreover, a single rod may be used. The depicted bow 500 utilizing two rods 532, 534, however, may help limit deflection. The rods 532, 534 may be connected to the riser 502 via set screws into riser 502, brackets or other mechanical elements, robust chemical adhesives, or combinations thereof. In alternative embodiments, risers may be manufactured from injection-molded plastics, and the rods may be formed integrally therewith. It may be desirable to reinforce such rods with internal support structures to increase rigidity.

The tensioning cable 524 is used to deflect the limbs 504, 506 of the bow 500, as described below. Two guide elements 536, 538 are located proximate the openings 528, 530, respectively, on the gearbox 526. The guide elements may be static elements, such as expanding or otherwise shaped channels to guide the tensioning cable 524 as it is drawn into and fed from the openings 528, 530. In other embodiments, one or more rollers 540, 542 spanning the raised portions of the guide elements 536, 538 may be used to reduce friction. The gearbox 526 defines an opening 544 through which a draw cable 546, ripcord, or other element may pass. The draw cable 546 is used to actuate the gear system located within the gearbox 526, as described below. The draw cable 546 extends from the opening 544 so that it may be easily grasped by a user of the bow 500.

FIG. 6 depicts a top view of the gearbox 526 with a top cover removed, exposing a gear system 600. The gearbox 526 includes an outer side wall 602, and an inner side wall 604. Here, the terms “outer” and “inner” are used to identify the wall relative to the location of the rods 532, 534. The gearbox 526 also includes a proximal wall 606 and a distal wall 608 (relative to the user of the bow 500). In brief and also referencing elements depicted in FIGS. 5A-5C, the gear system 600 will allow the user to store energy in the limbs 502, 504 by pulling on the draw cord 546. The gear system 600 will reduce the required draw force by using a number of gears and axles to create a mechanical advantage. A standard draw cycle for the depicted gear system 600 will require the user to pull the draw cord 546 twice to lock the limbs 502, 504 into a loaded or deflected position. Thereafter, the user may load a projectile on the bow string 522 to fire the projectile. In certain embodiments, the action of drawing the bow string 522 to a firing or drawn position may release the gear system 600, enabling the bow 500 to fire.

In the embodiment of FIG. 6, the gear system 600 includes three gear sections 600 a, 600 b, and 600 c, which are described in more detail below. These three 600 a, 600 b, and 600 c are also depicted in FIGS. 7A-7C, where the various pulleys, gears, etc., are shown spaced apart from each other for clarity. Although any spacing of these elements may be utilized, the elements are generally spaced as depicted in FIG. 6. In reference to FIGS. 6 and 7A, a tensioning gear system 600 a is shown and includes a tensioning axle 610 supports a tensioning pulley 612, ratchet 614, and a tensioning gear 616. The tensioning pulley 612 includes one or more screw clamps, pins, or other securing elements 618 that are used to secure the tensioning cable 524 to the tensioning pulley 612. As described above, the tensioning cable 524 passes through the openings (lower opening 530 is depicted in FIG. 6), and is wound partially around the tensioning pulley 612, supported in a groove 620 located along an outer edge thereof. In the depicted embodiment, the tensioning cable 524 is actually two cables discrete from each other. A first end of each cable is attached to either the superior axle 514 or the inferior axle 520. A second end of each cable is secured to either of the securing elements 618 a or 618 b. As the tensioning axle 610 rotates during use, each of the cables is guided into the circumferential groove 620. The tensioning gear 616 is configured to interact with one of the gears located on an intermediate axle 622.

Referring to FIGS. 6 and 7B, an intermediate gear section 600 b is shown and includes the intermediate axle 622 that supports a minor gear 624 and a major gear 626. The major gear interacts with one of the gears on a draw cord axle 628. Referring to FIGS. 6 and 7C, a draw cord gear section 600 c is shown and includes the draw cord axle 630 that supports a draw cord gear 632 and a draw cord pulley 634. The draw cord pulley 634 includes a screw clamp, pin, or other securing element 636 that is used to secure the draw cord 546 to the draw cord pulley 634. A spiral groove 638 provides a guide for preventing the draw cord 546 from becoming entangled as it wraps around an outer circumference of the draw cord pulley 634. Additionally, the draw cord gear section 600 c supports a clock spring that biases the draw cord pulley 634 toward an initial position. In the depicted embodiment, the clock spring is located within the draw cord pulley 634 and is not shown. Additionally, two linear springs located within spring housings 640 are configured to bias the draw cable axle 630 toward the distal wall 608, such that the draw cord gear 632 is not in engagement with the major gear 626 unless the draw cable 546 is being pulled toward the user. The linear springs may be sized such that pulling the draw cable 546 first pulls the draw cord gear 632 into an engaging configuration with the major gear 626, after which further pulling will rotate the draw cord pulley 634.

Operation of the depicted bow 500 begins with the bow 500 in a release position, where the bowstring 522 is positioned substantially linearly between the cams 508, 510. The release position is so named because this is the final position once an arrow has been launched or released. This is also the initial position of any bow prior to drawing the bow string to begin a shooting action. As the draw cord pulley 634 is rotated by pulling of the draw cord 546, the configuration of the gear system 600 compels rotation of the tensioning gear 616, which also rotates the tensioning pulley 612. This draws the tensioning cable 524 (or cables, as the case may be) around the tensioning pulley 612. This movement deflects the limbs 504, 506 from an initial position (also referred to as an equilibrium position) to a first deflected or pre-loaded position. At the end of the first pull of the draw cord 546, a pawl located within the gearbox 526 engages a first tooth of the ratchet 614. This locks the limbs 504, 506 in the first deflected position. This position may be referred to as a hold position for the bow 500. In the hold position, the bow 500 is unable to launch a projectile because the bow 500 is prevented from returning to the release position directly from the hold position, due to the interaction between the pawl and the ratchet 614. The clock spring then returns the draw cable pulley 634 to the initial position. A second pull of the draw cable 546 draws the limbs 504, 506 closer together, into a second deflected position. This second deflected position of the limbs 504, 506 may be referred to as a second hold position for the bow 500. The pawl engages a second tooth of the ratchet 614 and the clock spring again returns the draw cable pulley 634 to the initial position. This process of drawing the limbs 504, 506 into further deflected positions may continue as required or desired, until the maximum deflected position of the limbs 504, 506 is attained. In the depicted embodiment, however, only two draws to first and second bow hold positions are required.

At this point, a projectile such as an arrow may be knocked or secured to the bow string 522. To complete operation, the user first must draw the bow string 522 towards the user, as typical for use of a bow. To launch the arrow, the pawl first must be disengaged from the ratchet 614. This may be accomplished in a number of ways. In one embodiment, the draw of the bow to a ready or charged position will release the pawl, thus enabling launching of the arrow. In such an embodiment, the final draw of the bow string 522 will release tension from the tensioning cable 524 thus allowing the pawl to return to a disengaged position. In another embodiment, an electronic actuator located on the riser 502 may be actuated by, for example, the thumb of the user. The actuator may send a signal that actuates an electro-mechanical mechanism to move the pawl away from the ratchet 614. Additionally, the user may actuate a mechanical trigger connected by a cable or other linking element to the pawl. The ready position may be defined as the position from which the projectile may be launched, or the bowstring released in a controlled manner (and the projectile retained thereon). In either case, the depicted embodiment allows for movement of the bow to the release position only once the ready position is reached. In the ready position, the user will not hold a significant weight because the last portion of the draw will occur when the curvature of the cams 508, 510 are in the “let off” position, therefore the draw weight in this position will be greatly reduced. The “let-off” position refers to the point in a bow draw cycle when the cam lobes rotate to give a mechanical advantage to the user. At this point, much less force is required to keep the bow drawn. This will allow the average user to create the same energy as a standard compound bow while reducing the draw weight. The bow 500 may then be aimed and fired normally.

The gears used in the gear system 600 may be selected as desired or required for a particular application to obtain the desired gear ratios. In one embodiment, the gear system will produce an 8:1 mechanical advantage which will allow half the normal draw force while producing a similar energy output of a comparable unmodified bow system. Other ratios are contemplated. By the reducing the draw weight by half, the effective draw length must be doubled to produce a similar energy output. The reduced draw weight will allow people of limited upper body strength and others with limiting disabilities improved performance. In other embodiments, multiple pulleys may be used in conjunction with a clutch, ratchet, or other mechanism for holding the tensioning cable subsequent to each pull of a pulley string. The pulleys may be sized accordingly to provide the desired mechanical advantage when using the bow.

The technologies described herein are described in the context of handheld compound bows. However, a person of skill in the art will recognize the applicability of the disclosed technologies into other projectile-launching implements, for example, crossbows (compound or otherwise), ballistae, etc. Additionally, certain of the technologies, especially the gearbox configuration of FIGS. 5A-7C may be utilized in non-cammed bows, such as longbows, recurve bows, and composite bows.

While there have been described herein what are to be considered exemplary and preferred embodiments of the present technology, other modifications of the technology will become apparent to those skilled in the art from the teachings herein. The particular methods of manufacture and geometries disclosed herein are exemplary in nature and are not to be considered limiting. It is therefore desired to be secured in the appended claims all such modifications as fall within the spirit and scope of the technology. Accordingly, what is desired to be secured by Letters Patent is the technology as defined and differentiated in the following claims, and all equivalents. 

1. A projectile-launching device positionable in a release position wherein the device is unable to launch a projectile, a ready position wherein the device is able to launch a projectile, and a hold position located between the release position and the ready position, wherein the projectile-launching device comprises: a restraint system for preventing the device from being moved from the hold position directly to the release position; and a release mechanism for disengaging the restraint system so as to allow the device to be returned to the release position directly from the ready position, wherein the release mechanism disengages the restraint system when the device is moved to the ready position, and wherein the device is unable to launch the projectile from the hold position.
 2. The projectile-launching device of claim 1, further comprising a plurality of deflectable arms and at least one tensioning member connecting the plurality of arms.
 3. The projectile-launching device of claim 2, wherein the plurality of deflectable arms comprise: a superior primary limb and an inferior primary limb; and a superior secondary limb and an inferior secondary limb; and wherein at least one tensioning member comprises: a primary cable connecting the superior primary limb and the inferior primary limb; and a secondary cable connecting the superior secondary limb and the inferior secondary limb.
 4. The projectile-launching device of claim 3, wherein the restraint system holds the superior secondary limb and the inferior secondary limb in a deflected position, when the secondary cable is moved to a second cable drawn position.
 5. The projectile-launching device of claim 4, wherein the release system deactivates the restraint system when the superior primary limb and the inferior primary limb are moved to a deflected position.
 6. The projectile-launching device of claim 4, wherein the release system deactivates the restraint system when the primary cable is moved to a primary cable drawn position.
 7. The projectile-launching device of claim 3, wherein the restraint system comprises a ratchet and pawl located on at least one of the secondary limbs.
 8. The projectile-launching device of claim 7, wherein the release mechanism comprises an engagement element located on at least one of the primary limbs.
 9. The projectile-launching device of claim 3, wherein the primary cable is configured to releasably engage a projectile.
 10. The projectile-launching device of claim 2, further comprising a gearbox and a gear system comprising a tensioning member pulley located in the gearbox, wherein the tensioning element is wrapped at least partially around the tensioning member pulley.
 11. The projectile-launching device of claim 10, wherein the gear system further comprises a ratchet and a pawl releasably engaging the ratchet.
 12. The projectile-launching device of claim 11, wherein the release mechanism disengages the ratchet from the pawl.
 13. The projectile-launching device of claim 12, wherein the release mechanism comprises a trigger.
 14. The projectile-launching device of claim 12, wherein the release mechanism disengages the ratchet from the pawl when a bow string is moved from an undrawn position to an drawn position.
 15. The projectile-launching device of claim 11, wherein the gear system further comprises an actuator pulley and an actuator cable wrapped at least partially around the actuator pulley.
 16. The projectile-launching device of claim 15, wherein a free end of the actuator cable extends from the gearbox.
 17. A method of launching a projectile with a projectile-launching device comprising a release position, a hold position, and a ready position, the method comprising: moving the device from the release position to the hold position, wherein when in the hold position, the device is prevented from returning to the release position and from launching the projectile from the hold position; moving the device from the hold position to the ready position, wherein when in the ready position, the device is enabled to return to the release position and to launch the projectile; and releasing the device from the ready position to the release position to launch the projectile.
 18. The method of claim 17, further comprising automatically engaging a restraint mechanism when the device is moved from the release position to the hold position.
 19. The method of claim 18, further comprising automatically disengaging the restraint system when the device is moved to the ready position.
 20. A bow comprising: an upper limb and a lower limb; a tensioning cable and restraint system whereby energy may be stored in the upper limb and the lower limb via drawing the tensioning cable to a charged position; and a bow string that, via drawing the bow string to a ready position, releases the energy stored in the upper limb and the lower limb by the restraint system. 